I'm not sure what this "lead actress" means but if you mean "female lead" you are completely wrong. Halle was the biggest female star and the first female listed in the credits but that has nothing to do with who is the lead in a film.

In your other post you talk about Storm having some kind of lead in the films, but I strongly disagree. She is a textbook supporting character (and a poor one at that because she has unneeded screentime).

Film Storm as a character is extremely flat: she has no arc, we know nothing about her goals/desires or her past, we know nothing about her past, and we know little to nothing about her relationship with the other X-men (most notably the protagonist and antagonist of each movie).

Storm as a character has little or nothing that carries from film to film, Storm has no substantive involvement in the climaxes of ANY of the films. Actions that storm does take do not arise organically out her character: she just does stuff because someone has to do it for the sake of the story or because there's nothing else for her to do. Finally, Storm could easily be written out of each of the films without affecting the structure or integrity of the plot!

If you can present anything to dispute this, I would be very interested in hearing it (maybe you will prove me wrong!). I still think anyone who has ever written a script or knows anything about film structure or script development can recognize the pointlessness of the Storm character.

Well having your name at the top of the poster along with Hugh Jackman, I think that makes you the "lead actress" even if your role isn't that important to the story of the movie.